Plastic pin

ABSTRACT

A plastic pin having a porous and/or cellular core that is surrounded by a resilient shell is provided. The base of the pin is made of a different material than is the shell. The base is centrally provided with a plug that projects into the core. To improve the connection between the shell and the base, the outer side of the plug is provided with projections that form a positive connection with the core.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a plastic pin, i.e. one ofpolymeric material, for games, and has a porous and/or cellular corethat is surrounded by a tough or resilient shell. The pin has a basethat forms a support surface and that is made of a different materialthan is the shell. The base has a central bore and a plug or socket thatproceeds from the rim of the bore and extends into the core of the pin.

[0002] Within the context of the present application, plastic pins forbowling lanes include so-called bowling pins and nine pins.

[0003] It is desirable to use different materials for the base of thepin on the one hand, and for the shell thereof on the other hand; forexample, polyamides and polypropylenes are suitable for optimallysatisfying the specific requirements of different portions of the pin.However, during manufacture of the pins different materials do notalways provide the desired intimate bonding.

[0004] It is an object of the present invention to provide a good andimproved connection between the base of the pin on the one hand and thatportion of the pin shell disposed thereabove on the other hand.

BRIEF DESCRIPTION OF THE DRAWING

[0005] This object, and other objects and advantages of the presentinvention, will appear more clearly from the following specification inconjunction with the accompanying schematic drawing, in which:

[0006]FIG. 1 is a plan view of one exemplary embodiment of an inventivepin;

[0007]FIG. 2 is a partially cross-sectioned view of the lower portion ofthe pin of FIG. 1; and

[0008]FIG. 3 is a cross-sectional view of a modification of the pin ofFIG. 2, whereby the right and left portions of FIG. 3 show differentembodiments.

SUMMARY OF THE INVENTION

[0009] The pin of the present invention is characterized primarily inthat the plug that extends into the interior of the pin is positivelyconnected with the core of the pin by one or more projections. For thispurpose, the pin is expediently provided with circumferential ribs,which in turn preferably have a saw tooth shaped cross-sectionalconfiguration.

[0010] The plug of the base of the pin, and hence the base itself, arethus anchored to the core, whereby this anchoring can be the solesecuring means of the base, or an additional anchoring means can also beprovided.

[0011] The aforementioned anchoring can be very easily realized pursuantto the present invention. In particular, if the plug that extends intothe interior of the pin is provided with the aforementioned projections,and if the material that forms the cellular and/or porous plastic coreis introduced into the hollow interior of the pin from below through theplug during manufacture of the pin, the material of the core advancesdownwardly during introduction thereof to the inner side of the base,whereby such material surrounds the plug on all sides and therebycompletes the positive connection. In order in this connection not todisrupt the flow of material, it is advantageous to provide the basewith one or more fine venting bores.

[0012] Further specific features of the present invention will bedescribed in detail subsequently.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0013] Referring now to the drawing in detail, the pin of FIG. 1 isprovided in the customary manner in the base region with a base 1,thereabove a barrel or bulging portion 2, which merges into areduced-diameter neck 3, and finally a head 4 that has a smaller outerdiameter than does the barrel 2. The components 2, 3 and 4 form theshell 5 of the pin. The pin is additionally provided with a core 6 thatis preferably adhered or secured to the outside. The core 6 comprises acellular and/or porous polymeric material and, after completion of theouter casing (the base 1 and the shell 5), is formed by introducing anexpanding material into the interior of this casing through the centralbore 7 in the base 1.

[0014] Whereas the shell 5 is comprised of a polymeric material based onpolypropylenes, the base 1 is made of a generally harder polymericmaterial based on polyamide. Although these materials are suitable, theydo not always form an adequately strong bond with one another.

[0015] From the rim of the bore 7 in the base 1, a socket or plug 8extends perpendicularly upwardly, i.e. into the interior of the pin, forexample having a length of about 40-80 mm. The important feature is thatthe outer surface of the plug 8, which is monolithically formed with thebase 1, is provided with a plurality of annular projections 9 that aredistributed over the height of the plug 8. The annular projections 9preferably have a saw toothed cross-sectional configuration, and inparticular such that the larger diameter portion of the projections 9face the base 1, thus creating corresponding undercuts.

[0016] When the material that forms the core 6 is introduced it passesnot only into the barrel 2, the neck 3 and the head 4, but also in thedirection of the arrows 10 into the region of the base 1, whereby thetrapped air can escape via small bores 11 in the base 1. The plug 8 isthereby surrounded. The strengthening and reinforcing material of thecore forms a positive connection between the core 6 and the plug 8 andhence the base 1. This means that the base 1 is securely connected tothe shell 5.

[0017] In order to preclude a lateral shifting, the base 1 can belaterally provided with a rim or flange 12 (shown by dashed lines) thatcenters the components 1 and 5 relative to one another.

[0018] If desired, an adhesive can be effective in the region of theseparating faces between the shell 5 and the base 1. However, theconnection of these components is often adequately ensured by theaforementioned positive connection.

[0019] In the embodiment illustrated in FIG. 3, where the core 6 is notshown, the base 1 is provided with an upwardly widening plug 8, in otherwords, a plug that has an essentially conical exterior surface (thediameter D is greater than the diameter d). This plug 8 also results ina positive connection, i.e. forms a back taper or undercut for thematerial of the core.

[0020] In addition, a hook connection can also be provided between theshell 5 and an upwardly extending rim 13 of the base 1. For thispurpose, the shell 5 can engage in an inwardly disposed circumferentialgroove 14 of the rim 13 (as shown in the left half of FIG. 3), or theshell 5 can engage in an outwardly disposed circumferential groove 15 ofthe rim 13 (as shown in the right half of FIG. 3).

[0021] It should be noted that in place of the annular, circumferentialprojections 9, it would also be possible to use knobs or studs, in otherwords, projections that extend over only a portion of the periphery ofthe shell. However, the expedient feature in each case is thatadequately large undercuts be provided. A saw tooth configuration istherefore very suitable. In addition, in place of the hook connection itwould also be possible to use a differently configured tongue and grooveconnection.

[0022] The specification incorporates by reference the disclosure ofGerman priority document 100 18 917.2 of Apr. 17 2000.

[0023] The present invention is, of course, in no way restricted to thespecific disclosure of the specification and drawing, but alsoencompasses any modifications within the scope of the appended claims.

What I claim is:
 1. A plastic pin, comprising: a resilient shell thatsurrounds a core of porous and/or cellular material; a base that adjoinssaid shell and provides a support surface for the pin, wherein said baseis made of a material that differs from the material of said shell, andwherein said base is provided with a central bore; and a plug thatextends into said shell from a rim region of said central bore, whereinan outer side of said plug is provided with at least one projection toprovide a positive connection with said core.
 2. A pin according toclaim 1, wherein said at least one projection has a saw toothedcross-sectional configuration, wherein a portion of said projection thatfaces said base extends further from said plug than does a portion ofsaid projection that faces from away said base.
 3. A pin according toclaim 1, wherein a plurality of annular projections are distributed overa length of said plug.
 4. A pin according to claim 1, wherein ventingbores are disposed in said base.
 5. A pin according to claim 1, whereinsaid plug has an at least partially conical configuration, with a largerdiameter portion of said plug being disposed at a free end of said plugand forming said at least one projection thereof.
 6. A pin according toclaim 1, wherein said base is provided with a circumferential flange forcentering said shell on said base.
 7. A pin according to claim 1,wherein said base is provided with a projecting rim that engages anassociated rim of said shell in a hook-like or tongue and groove manner.8. A pin according to claim 1, wherein said plug is monolithicallyformed with said base and extends essentially perpendicular to saidbase.